Riding Honda's U3-X Unicycle of the Future

It only has one wheel, but Honda's futuristic personal mobility device, called the U3-X, is no pedal-pusher. The unicycle of the future moves as you move, wheeling you to your destination simply by sensing your body tilting this way or that, Segway style.

Honda says the machine is designed for indoor use, but last week, when the company demoed it for us in New York, it worked just fine in Times Square. Watching the Honda engineers riding it around on a Broadway sidewalk was like getting a glimpse of the future.

I also got a chance to try the U3-X -- not on Broadway, but at a hotel conference room nearby. Following the instructions of the cheerful Shin-ichiro Kobashi, the U3-X lead engineer, I hopped on the seat and took a few seconds to orient myself.

After some tentative leaning to test how far I could go without falling, I got a feel for the device and found it simple to navigate. You just lean slightly in the desired direction and off you go.

It's definitely a trip. The footrests are there just for balance, not to steer. Your hands stay free, and you're perched just a little below eye level, at a height that's still natural to talk to someone standing up. Putting your feet down helps stop and turn, especially if you're rapidly approaching a wall in front of you. And the whirring of the machine is so satisfying!

Watch the video to see how easy it is to ride it:

The U3-X uses a balance control system that derives from Honda's research on human walking dynamics for its famed Asimo bipedal humanoid robot.

When the rider leans his or her body, an angle tilt sensor sends data to the balance control system, which in turns moves the wheel, maintaining balance.

But the amazing thing about the U3-X is not quite visible: its omnidirectional wheel.

The wheel consists of a ring of small rubber wheels overlapping a single large wheel (see illustration below). When the large wheel rotates, the U3-X moves forward or backward. When the small wheels rotate, the machine moves left or right. And when both the large and small wheels turn at the same time, the U3-X moves diagonally.

Honda showed us animations but didn't let us take photos of the wheel itself. It's a really ingenious system that uses only two motors to accomplish all of its movement.

So how fast can it go? Its has a top speed of 6 kilometers per hour, which is a little better than the average walking speed of an adult, and the lithium-ion battery will let you ride around for an hour.

The machine weighs less than 10 kilograms (22 pounds) and max rider weight is currently 100 kg (220 lb).

Because it's such a narrow device, no wider than the distance between your legs, it won't get in the way of other pedestrians or riders on crowded streets on in an office environment, Kobashi explained.

The seat folds down and the footrests fold up, so it fits in a compact package that looks a bit like a slim boombox. It's not George Jetson's foldable space car, but you can grab it by the handle and roll it around like a suitcase.

But the questions many passersby at Times Square asked were, "Where do I get one," and "How much does it cost?" Alas, Honda doesn't know that yet. Guess we'll have to wait for the future to come.

Some more photos of the device in Times Square and slides from a technical presentation the Honda engineers gave us: